Fragmentation of Positronium (Ps) in collision with Li ion

Fragmentation of ground state ortho Positronium (Ps) in collision with Li ion (Li+) is studied in the framework of post collisional Coulomb distorted eikonal approximation (CDEA) for the target elastic case . The present model takes account of the two center effect on the ejected e which is crucial for a proper description of the projectile ionization involving an ionic target. Both the fully differential (TDCS) and the doubly differential (DDCS) cross sections (energy spectra) are investigated at intermediate and high incident energies. A broad distinct Electron loss peak (ELP) centered around v_e ~ v_p is noted in the e energy spectrum in contrast to the sharp ELP for a heavy projectile. Two salient features are noted in the present study: i) the shift of the e DDCS peak (summed over e+ angles) towards higher ejection energy with respect to half the residual energy of the system, ii) comparison of the e& e+ energy spectra reflect a strong e - e+ asymmetry with respect to the ratio v_e/v_p =1 >. Both these features could be attributed to the post collisional two center effect on the e due to its parent nucleus (e+) and the screened target ion . Two different wave functions of the Li ion are chosen in order to test the sensitivity of the present results with respect to the choice of the wave function.Comment: 19 pages, 7 figure

Relativistic time dilatation and the spectrum of electrons emitted by 33 TeV lead ions penetrating thin foils

We study the energy distribution of ultrarelativistic electrons produced when a beam of 33 TeV Pb$^{81+}$(1s) ions penetrates a thin Al foil. We show that, because of a prominent role of the excitations of the ions inside the foil which becomes possible due to the relativistic time dilatation, the width of this distribution can be much narrower compared to the case when the ions interact with rarefied gaseous targets. We also show that a very similar shape of the energy distribution may arise when 33 TeV Pb$^{82+}$ ions penetrate a thin Au foil. These results shed some light on the origin of the very narrow electron energy distributions observed experimentally about a decade ago.Comment: Four pages, two figure

Role of charge patches in ion guiding through nanocapillaries in a PET polymer

We studied the dynamic properties of ion guiding through nanocapillaries in insulating polyethylene terephthalate (PET). The angular distribution of the transmitted ions was measured as a function of time. The temporal evolution of the angular transmission profiles was acquired for the capillary diameters of 200 and 400 nm. The tilt angle was varied from 0° to 6.5°. The transmission profiles exhibit significant changes in position as time varies. This observation is explained by the formation of temporary charge patches produced in the interior of the capillary besides the primary charge patch created in the entrance region.</p

The Role of Bulk and Interface Recombination in High‐Efficiency Low‐Dimensional Perovskite Solar Cells

2D Ruddlesden–Popper perovskite (RPP) solar cells have excellent environmental stability. However, the power conversion efficiency (PCE) of RPP cells remains inferior to 3D perovskite-based cells. Herein, 2D (CH(CH)NH)(CHNH)PbI perovskite cells with different numbers of [PbI] sheets (n = 2–4) are analyzed. Photoluminescence quantum yield (PLQY) measurements show that nonradiative open-circuit voltage (V) losses outweigh radiative losses in materials with n > 2. The n = 3 and n = 4 films exhibit a higher PLQY than the standard 3D methylammonium lead iodide perovskite although this is accompanied by increased interfacial recombination at the top perovskite/C interface. This tradeoff results in a similar PLQY in all devices, including the n = 2 system where the perovskite bulk dominates the recombination properties of the cell. In most cases the quasi-Fermi level splitting matches the device V within 20 meV, which indicates minimal recombination losses at the metal contacts. The results show that poor charge transport rather than exciton dissociation is the primary reason for the reduction in fill factor of the RPP devices. Optimized n = 4 RPP solar cells had PCEs of 13% with significant potential for further improvements

120kev Ar8+-li Collisions Studied By Near Uv And Visible Photon Spectroscopy

A spectroscopic analysis of light emitted in the 200-600 nm wavelength range by Ar7+, Ar6+ and Ar5+ ions after charge exchange in 120keV Ar8+-Li collisions is performed. Transitions with Δn = 1 and Δn = 2 for n = 8, 9, 10 and 11 states of Ar8 following single electron capture are identified and the production cross sections for n = 8 and n = 9 are deduced from emission cross sections and compared with those calculated by the three-body classical trajectory Monte-Carlo method. Lines due to double capture process were observed and identified as Rydberg transitions 3snl-3sn\u27l\u27 (n = 7, 8 and 9) in Ar VII. Lines due to triple electron capture process were found and identified as transitions 3s2nl-3s2n\u27ï and 3s3pnl- 3s3pril\u27(n = 7, 8) in Ar VI. The configurations produced during the collision provides evidence that electron-electron interaction play an important role in double and triple charge exchange processes. © 1993 IOP Publishing Ltd

High-order Harmonic Spectroscopy of the Cooper Minimum in Argon: Experimental and Theoretical Study

We study the Cooper minimum in high harmonic generation from argon atoms using long wavelength laser pulses. We find that the minimum in high harmonic spectra is systematically shifted with respect to total photoionization cross section measurements. We use a semi-classical theoretical approach based on Classical Trajectory Monte Carlo and Quantum Electron Scattering methods (CTMC-QUEST) to model the experiment. Our study reveals that the shift between photoionization and high harmonic emission is due to several effects: the directivity of the recombining electrons and emitted polarization, and the shape of the recolliding electron wavepacket.Comment: 13 page

Post-Prior discrepancies in CDW-EIS calculations for ion impact ionization fully differential cross sections

In this work we present fully differential cross sections (FDCSs) calculations using post and prior version of CDW--EIS theory for helium single ionization by 100 MeV C$^{6+}$ amu$^{-1}$ and 3.6 MeV amu$^{-1}$ Au$^{24+}$ and Au$^{53+}$ ions. We performed our calculations for different momentum transfer and ejected electron energies. The influence of internuclear potential on the ejected electron spectra is taken into account in all cases. We compare our calculations with absolute experimental measurements. It is shown that prior version calculations give better agreement with experiments in almost all studied cases.Comment: 9 pages, 7 figure